Local acute inflammation is protective and ideally should be self-limited. Our recent evidence indicates that resolution of sterile acute inflammation is an active process with the identification of novel specialized proresolving lipid-derived mediators (SPM) we coined resolvins and protectins. These local mediators possess potent anti-inflammatory and pro-resolving actions. It is now evident that the resolution of inflammation caused by apoptotic cells or bacterial invasion in model in vivo systems remains largely uncharted and is critically needed. The focus of Project 1 in this program project is the systematic elucidation of resolution components during self-limited verses un-resolved inflammation using an unbiased mediator-lipidomics approach with exudates. Using this approach, we recently uncovered a new family of lipid mediators coined maresins (macrophage mediators in resolving inflammation; MaR) that actively regulate both neutrophils (PMN) and macrophages. Project 1 will test the following novel hypothesis : During self-limited inflammation local production of novel anti-inflammatory and pro-resolving mediators in exudates enhances the clearance of apoptotic cells and microbes for timely resolution. Resolvins, protectins and maresins are a newly identified genus of SPM that temporally govern PMN and macrophage responses required for tissue resolution and return to homeostasis. To address this, 3 specific aims are proposed: 1) Determine temporal relationship between resolvin and protectin (SPM) biosynthesis during resolution. We will determine the key events involved in self-limited resolution with SPM and with Projects 2 and 3; 2) Activation of novel maresins and resolvins during resolution. MaR display potent anti-inflammatory and proresolving actions. This aim will focus on MaR biosynthesis and stereochemistry with Projects 4 and will establish pro-resolving and protective actions in models of human disease with Core C and 3) Impact of maresins and resolvins in phagocyte responses in resolution. Here, we will identify SPM that accelerate resolution, clearance phagocyte anti-microbial activities in mice and human phagocytes. Together results from these will establish the role of novel SPM in resolution of inflammation.